The General Services Adminstration ordered yesterday the inspection of all PCB transformers in federal buildings nationwide to ensure that they comply with Environmental Protection Agency regulations, a GSA spokesman said.

The order from William F. Sullivan, GSA's public buildings commissioner, went to 11 regional commissioners and included a warning that EPA regulations define "leaks" in PCB transformers as any moisture that collects enough to drip, according to Ted Leininger, public buildings commissioner for the National Capital Region.

Previously, some confusion existed about what constituted leaks, with some preferring to call them "weeps" or "seeps."

PCBs, or polychlorinated biphenyls, are cancer-causing agents that were once the most widely used coolant for high-voltage transformers. Though flame retardant, when they are involved in fire they give off toxic fumes such as dioxins, which are about 1,000 times more deadly than PCBs in their liquid state.

GSA spokesman Joseph M. Slye said that 1,500 PCB transformers in GSA-owned buildings around the country will be inspected. He said that the commissioners will compile a list of the transformers' locations and an inventory of their leaks for immediate repairs.

GSA officials have said that more than 80 of the nearly 800 PCB transformers in federal buildings in the Washington area have leaks, most of which are relatively minor.

Sullivan's order followed, but was not prompted by, reports of leaking PCB transformers in the Smithsonian Institution and the White House complex, according to Slye.

He said that the GSA will attempt to replace or "retrofill" all of its PCB transformers by the end of fiscal 1988, two years ahead of the deadline set by EPA regulations released last month. Retrofilling a transformer is a process during which the PCBs are drained and replaced with a nontoxic coolant.

Replacing or retrofilling all of GSA's PCB transformers will cost about $120 million, Slye said.